The present invention relates to an improvement in the construction of permeation devices in general and, more particularly, to coil-type dialyzers used in artificial kidney systems. Although the description of the invention herein is based on its use as a dialyzer of the type used in artificial kidneys it may also be used in other mass transfer applications.
Numerous coil artificial kidney devices are known which comprise a flattened tubular semipermeable membrane wound about a rigid pre-formed core member with the membrane winding layers being separated by membrane support material. Additional components of such coil dialyzers include a cylindrical outer case, upper and lower end caps for the cylindrical case, inlet and outlet ports for blood flow, and inlet and outlet ports for dialysis solution flow. Examples of such coil kidneys are disclosed in Miller U.S. Pat. No. 3,508,662, van Assendelft U.S. Pat. No. 3,892,664 and Miller U.S. Pat. No. 4,009,108.
In operation coil dialyzers may be either totally enclosed or partially enclosed. In both types blood to be dialyzed flows through the interior of the wound flattened tubular semipermeable membrane while a dialyzing fluid flows over the outer surface of the membrane thereby removing blood impurities which have passed through the semipermeable membrane. The totally enclosed coil dialyzer has integral ports for introducing and removing dialyzing fluid and blood. All fluids are contained or enclosed in the dialyzer itself. By contrast, the partially enclosed coil dialyzer sits in a bath of dialyzing fluid and the circulation of the fluid in the bath causes dialyzing fluid to flow between the windings of the semipermeable membrane and thereby remove blood impurities which have migrated to the exterior of the membrane. A partially enclosed coil dialyzer is disclosed in the Miller U.S. Pat. No. 3,508,662.